Toulmin's Argument Model

Stephen Toulmin, an English philosopher and logician, identified elements of a
persuasive argument. These give useful categories by which an argument may be
analyzed.

Claim

A claim is a statement that you are asking the other person to accept. This
includes information you are asking them to accept as true or actions you want
them to accept and enact.

For example:

You should use a hearing aid.

Many people start with a claim, but then find that it is challenged. If you
just ask me to do something, I will not simply agree with what you want. I will
ask why I should agree with you. I will ask you to prove your claim. This is
where grounds become important.

Grounds

The grounds (or data) is the basis of real persuasion and is made up
of data and hard facts, plus the reasoning behind the claim. It is the 'truth' on which
the claim is based. Grounds may also include proof of expertise and the basic
premises on which the rest of the argument is built.

The actual truth of the data may be less that 100%, as much
data are ultimately based on perception. We assume what we measure is true, but
there may be problems in this measurement, ranging from a faulty measurement
instrument to biased
sampling.

It is critical to the argument that the grounds are not challenged because,
if they are, they may become a claim, which you will need to prove with even
deeper information and further argument.

For example:

Over 70% of all people over 65 years have a hearing
difficulty.

Information is usually a very powerful element of persuasion, although it does
affect people differently. Those who are dogmatic, logical or rational will more
likely to be persuaded by factual data. Those who argue emotionally and who are highly
invested in their own position will challenge it or otherwise try to ignore it.
It is often a useful test to give something factual to the other person that
disproves their argument, and watch how they handle it. Some will accept it
without question. Some will dismiss it out of hand. Others will dig deeper,
requiring more explanation. This is where the warrant comes into its own.

Warrant

A warrant links data and other grounds to a claim, legitimizing the claim by showing the
grounds
to be relevant. The warrant may be explicit or unspoken and implicit. It answers
the question 'Why does that data mean your claim is true?'

For example:

A hearing aid helps most people to hear better.

The warrant may be simple and it may also be a longer argument, with
additional sub-elements including those described below.

In many arguments, warrants are often implicit and hence unstated. This gives
space for the other person to question and expose the warrant, perhaps to show
it is weak or unfounded.

Backing

The backing (or support) for an argument gives additional support to the warrant by
answering different questions.

For example:

Hearing aids are available locally.

Qualifier

The qualifier (or modal qualifier)indicates the strength of the leap from the data to the
warrant and may limit how universally the claim applies. They include words such as 'most', 'usually', 'always'
or 'sometimes'.
Arguments may hence range from strong assertions to generally quite
floppy with vague and often rather uncertain kinds of statement.

For example:

Hearing aids help most people.

Another variant is the reservation, which may give the possibility of
the claim being incorrect.

Unless there is evidence to the contrary, hearing aids do no
harm to ears.

Qualifiers and reservations are much used by advertisers who are constrained
not to lie. Thus they slip 'usually', 'virtually', 'unless' and so on into their
claims.

Rebuttal

Despite the careful construction of the argument, there may still be
counter-arguments that can be used. These may be rebutted either through a
continued dialogue, or by pre-empting the counter-argument by giving the
rebuttal during the initial presentation of the argument.

For example:

There is a support desk that deals with technical problems.

Any rebuttal is an argument in itself, and thus may include a claim, warrant,
backing and so on. It also, of course can have a rebuttal. Thus if you are
presenting an argument, you can seek to understand both possible rebuttals and also rebuttals
to the rebuttals.